Cleaning and Shaping Flashcards
What are the basic principles of shaping?
- A constantly tapering funnel from crown to WL
- Curves of canal respected w/o “transportation”
- Retention of the “apical constriction”
- Enlargement of the canal system to create clean white filings
- Adequate “deep space” for proper obturation
What are the 9 steps (following a proper access)?
- Scouting
- Patency
- Working Length
- Glide Path
- Shaping of coronal 1/3 of canal
ONLY HAND FILES to this point - Shaping of middle 1/3 of canal
- Perfecting Straight-Line-Access to mid root
- Shaping of apical 1/3 of canal
- Final Shaping Objective
What file do you use for scouting?
10 hand file
How do you perform scouting?
take a #10 hand file and gently perform watch winding motion (right and left rocking motion)
What is performed at the same time as scouting?
patency
When do you know the canal is patent?
10 file goes slightly beyond the canal exit (0.5mm) into the periodontal ligament
How do you find patency in clinic?
apex locator
How do you find patency in clinic?
measure the tooth before you mount it
Patency is maintained by…
Recapitulation (irrigating and revisiting patency after Wave One with the patency file #10 only the canal The Apex)
If it is tight resistance to apical advancement you probably have a…
small canal which must be enlarged carefully
If it is loose resistance to apical advancement you probably have a…
canal curvature and you must bend the terminal flute of your file
What do you do if you do if you cannot reach patency?
DON’T FORCE IT
- ask faculty for help
What does the single red line on the apex locator indicate?
patency
All shaping is done at the…
working length (1 mm short of canal exit)
The working length is __mm short of canal exit?
1 mm
What is the reference point for working length on anteriors?
Incisal edge
What is the reference point for working length on posteriors?
Cusp for which canal is named, flatten cusp when possible
How do you tell if canals converge or are simply 2 canals in close proximity?
- Establish working length of “each canal” separately
- Attempt to place 2 files to WL in each Canal @ same time
- If both go to WL = 2 canals (Class III canals)
- If one goes & the other is short – reverse the placement sequence. If still one is short = converging Class II canals
During the two file technique if both files go to the working length then…
2 canals (class III)
During the two file technique if one goes to working length and one is short then…
converging class II canals
What is the purpose of creating a smooth “glide path”
- To smooth curves & make sure there are no canal obstructions
- To create space for rotary instruments to be used safely without excessive torque requirements.
- To relieve stress on tip of rotary file to minimize fracture
The glide path is created using…
hand files (pre-curved to match or slightly exceed the curvature of the canal)
What is the process to create a smooth “glide path”?
- using hand files in a watch-wind entry follow by pull strokes directed in a circumferential manner to enlarge the canal to size #15 at the working length
The operator action is a ___________ motion when shaping the canals by thirds
light “pecking”
As the ________ action tends to push debris ahead of the file so stop action at 1/3 and 2/3 of the operation approaching the apex to clean the file and to irrigate thoroughly at these stages of shaping
Wave One
__________ following each active instrument (revisit patency 2-3 times during cleaning and shaping)
Irrigate
If a 10 K-file was very resistant to movement, use Wave One Gold ____ file
Small
If a 10 K-file moves to length easily, is loose or very loose, use Wave One Gold ______ file
Primary
If a 20 hand file or larger goes to length, use Wave One Gold _____ file
Large
The Crown usually is about 10mm of total tooth length. The root is mentally divided into _______
thirds
We will be shaping the canal _____ at a time
1/3
How do you perfect straight-line-access to mid root?
- Place a .25/.08 Vortex Orifice opener in the Pro-Mark motor and adjust the action to Vortex and leave the speed at 500 rpm.
- Allow the 25/.08 to mill to the depth of mid root ONLY
When do you perfect straight-line-access to mid root?
Following 2nd 1/3 (Wave One shaping)
How do you shape the apical 1/3 of the canal?
- Set the Wave One Gold file at the confirmed WL and reset the Pro-Mark motor to reciprocal action
and guide it to advance to the WL. - Confirm patency & smooth glide path with #15 hand file & then irrigate and continue to WL with Wave One.
- IRRIGATE
What do you do after every time you use a file?
irrigate
What file do you use to do the final shaping?
Vortex Blue Files for the final shaping and smoothing of the canal
How do you use the vortex blue files?
Each Vortex Blue file should be
KEPT MOVING and go completely to WL on each of 10 strokes. They should be flexed while rotating & being drawn out to away from
increase the flare furca of the canal in an appropriate direction or toward the greater dimension of the canal.
How do you know when the final shaping is done?
Shaping is complete when dentinal filings are on apical 1/3 of the instrument
Small Roots about #_____ MAF
30-35
Medium Roots about #_____ MAF
40-45
Large Roots are #____ MAF or
more
45-50
Teeth with moderate to severe curvature require ________ MAF avoid transportation of canal
smaller
Younger teeth will have larger
canals & require _______ MAF to clean
larger
What is the serial step-back method?
a method of producing a greater taper at the apcial control zone (used when the canal requires a larger diameter than the .45/.04 vortex blue file)
What teeth do you use a small MAF (master apical file)?
Mand. Incisors, 2 canal Premolars, M. canals of Mand. molars, B. canals of Max. Molars
What teeth do you use a medium MAF (master apical file)?
Palatal canals of Max. Molars, Single Distal canals of Mand. Molars
What teeth do you use a large MAF (master apical file)?
Max. Anteriors, M/M Cuspids, Single canal M/M Premolars
How can you tell the degree and location of curvature (mesial and distal)?
radiograph
_______________ curves will NOT generally be seen on radiographs
Facial and lingual
How can you see the facial and lingual curves on radiographs?
–Try angled radiographs (SLOB)
–Look for “bulls eye”radiograph (root tip turns to F or L)
–If your initial #10 SS scouting file bends (it follows the anatomy of the canal)
How do you accidentally create ledges and blockages?
When we place a straight SS hand file in a curved canal
- Tends to gouge (convex) wall of the and lean against the outside creating the a Ledge, which can be the first step to Blockage or Transportation
If we keep Pushing & Grinding against a ledge on the file, we can eventually force it through the root to create a…
Perforation
As our shaping proceeded to the larger sizes of SS hand files above #15 :
-Increase in Stiffness
-Decrease in Flexibility
What is a zip?
Transportationof apex occurs within the root
If the Zipoccurs the through apex to the exterior of the root. We have an…
apical strip perforation
Transportation is one of the
MAIN REASONS that we selected
the current technique in which
hand files used are generally no
larger than…
15
You are encountering a ledge
bend or curve; what do you do?
- Do Not Force File: Instead STOP Irrigate, and Bend file at the Tip (approx. 2mm)
- The most apical flutes of the file must be bent and rotated to track the inside wall of the canal.
What is a strip-perforation?
- Occurs when files used are either too large or too aggressively used for a small or thin walled canal
- invagination on the distal aspect of the mesial root of mandibular molars
When do strip-perforations usually occur?
Commonly the distal of the mesial root of lower molars, MF of upper molars, 2 canal max. PM
What can happen if there is a severe curve in the canal – especially if the curve occurs in the apical 1/3 and a smooth glide path was not perfected and the operator tries to PUSH or Force the Wave One Gold file to WL?
Transportation
What can happen if you allow the vortex blue file to rotate at or slightly short of the working length for more than a moment?
transportation
KEEP THE VORTEX BLUE FILE __________ at or slightly short using a smooth in-out motion in the canal while flexing the walls
MOVING
What does this show?
strip perforation
What does this show?
transportation
What does this show?
ledge creation
